The present application relates to vehicles configured to deliver and release pesticide compositions in a controlled manner, and more particularly but not exclusively, to degradable capsules formed of a gelatin material and encapsulating a pesticide composition.
Fields, groves, orchards and other plant growing environments can be infested with various pests, non-limiting examples of which include soil-borne plant pathogens and/or plant parasitic nematodes. When such infestations involve soil-borne plant pathogens and/or plant parasitic nematodes, soil fumigation is often the best or only economical method of reducing these pest populations sufficiently to produce high quality and high yielding plant crops, including for example fruits and vegetables. In one application technique, a fumigant in a liquid or vapor phase is injected into the soil through a delivery nozzle inserted into the soil to a desired depth. When injected in a liquid phase, the fumigant converts to a gas that spreads out in the soil surrounding the site of injection.
In most instances, the application of fumigants utilizing this technique yields acceptable control of targeted pests. However, it is not free from shortcomings and undesirable side effects. For example, one problem that arises in connection with the use of this technique is exposure of workers to noxious and dangerous fumes. Another problem with this technique is that a significant portion of the volatile substances in the fumigants commonly escape into the atmosphere. This is often due to the inability to precisely control the dosage and/or release of the fumigant. In turn, ground level ozone is generated from the reaction of the volatile fumigant with nitrogen oxides in the troposphere, and it can be harmful to respiratory systems of animals and damage sensitive plants. It is also believed that volatile substances used in certain fumigants may play a role in global ozone depletion in the Earth's upper atmosphere, which is known to be associated with a variety of negative consequences.
To reduce the loss of fumigants into the atmosphere, and the resulting loss of fumigant efficacy, a covering material such as a polyethylene sheet or tarp is sometimes utilized to cover the soil after application of the fumigant. The polyethylene tarp, although not impervious to gases, can reduce the dissipation rate of gases into the air, and thus prevent the depletion of the volatile fumigants by evaporation into the atmosphere. Nonetheless, covering the soil with these materials is labor-intensive, complicated and requires special application equipment, and workers are still exposed to noxious and dangerous fumes. In addition, the use of capsules which contain the fumigant and are applied via implantation into the soil has been advanced as an approach for overcoming the above identified shortcomings and undesirable side effects. However, even with these advances, controlling the release of fumigant from the capsule is problematic. For example, in many cases the fumigant is untimely released, in whole or in part, during shipping, storage or other handling of the capsules. This leads to decreased effectiveness of the implanted capsules and also exposes workers handling the capsules to the fumigant. In addition, control of the time and rate at which the fumigant is released following implantation of the capsule into the soil is still inadequate, and ground level ozone can still be present in some instances. Accordingly, there is a demand for further improvements in this area of technology.